Water stressed have vital effect on the various anatomical, physiological and bio-chemical processes, which are controlled by genetic and prevailing environment. In present study, 25 wheat (Triticum aestivum L.) cultivars, which have been released over 40 years in Iran, were evaluated in terms of stem physiological and anatomical changes at Iran Agricultural Research Station. During growing season data were collected and finally crop was harvested in June and various anatomical aspects like Thickness of stem (TS), Thickness of fiber (TF), Tangential dimension of collenchymas cells (TDC), Tangential dimension of vascular bundle (TDVB), Radial dimension of vascular bundle (RDVB), Radial dimension of big xylem vessel (RDBXV), Tangential dimension of phloem bundle (TDPB), Distance between vascular bundle to Epidermis (DBVBE), Thickness of epidermal cell (TE) that are integral part of drought resistance were studied. Predominantly drought resistant genotypes were recorded with anatomical aspects which play major role in imparting drought resistance. Among the studied 25 genotypes, genotype number 7, 21 and 25 showed maximum drought resistance characteristics collectively and these can be used as parent cultivars for future breeding programs.

Wheat (Triticum aestivum L.) is known as a drought semi-tolerant species. Reduction in wheat growth and yield are the most common responses to drought or salt stress mainly caused by an inhibition of leaf expansion and stem elongation. One of the important abiotic stress factors limiting wheat production in semi aridregions is drought. Recent climate changes such as temperature changes and decreasing rainfall in different regions of Iran have had significant impact on agroecosystems and have caused drought stress to become a severe limiting factor in wheat production. This research was conducted for evaluation of leaf anatomical and cytological traits of 26 wheat varieties in Golestan province (Iran) over 40 years in order to identify the most effective traits in determining maximum yield potential. The width and length of vascular bundles, diameter of meta xylem, distance between vascular bundles to upper and lower epidermis, fiber bundles diameter and width of midrib and lamina were measured. Finally, based on the anatomic results, wheat varieties with the highest adaptation ability to drought stress were identified and introduced.